Right after its birth, the Universe wasn't just expanding: it was inflating at an unimaginable pace. This stage, called inflation, was proposed by Alan Guth. New models compare the process to inflating a balloon with quick, jerky pumps. If the pump hesitates for a moment between strokes, the balloon shrinks slightly and then pops with a crisp snap. So it is with the Universe: a fleeting pause leaves a surge of gravitational waves — ripples in space itself.
Over the eons, these waves have stretched along with the cosmos, and now they ripple at frequencies within reach of future detectors. Instruments like the Einstein Telescope will capture not individual “bangs,” but a constant background hum.
Detecting this signal would be the first direct evidence of how the Big Bang was triggered and the large-scale structure of the universe began to form.
It’s astonishing: oscillations born in that elusive instant might soon be registered right here on Earth.
The delay that gave rise to these waves was billions of billions of times shorter than the time it takes light to cross an atom.